Multiple-Input Multiple-Output Low-Noise Block Downconverter and Low-Noise Module

ABSTRACT

A low-noise block downconverter (LNB) is disclosed. The low-noise block downconverter comprises a first input module, for outputting a first intermediate frequency (IF) signal after receiving a first polarization signal via a first input end; a second input module, for outputting a second IF signal after receiving a second polarization signal via a second input end; a first output module, coupled to the first input module, for amplifying the first IF signal, to output a first user signal to a first user; and a second output module, coupled to the second input module, for amplifying the second IF signal, to output a second user signal to a second user.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a multiple-input multiple-output (MIMO)low-noise block downconverter and a MIMO low-noise block module, andmore particularly, a MIMO low-noise block downconverter and a MIMOlow-noise block module are capable of providing a plurality ofpolarization signals to a plurality of users according to choices of theplurality of users.

2. Description of the Prior Art

Satellite communication has several advantages, such as a wide coverage,low terrestrial interference, etc., and has been applied to many areassuch as television broadcasting and wireless communication. Further,satellite signals can be received regardless of a position (e.g. a citywithout infrastructure, ocean or desert) of a receiver, as long asreceiving antennas of the receiver are properly configured.

Please refer to FIG. 1, which is a schematic diagram of a satellitebroadcasting system 10 according to an example of the prior art. Thesatellite broadcasting system 10 is suitable for a family, a building ora community. Each user in the family, the building or the community canreceive satellite signals, such as Ku band (10.7-12.75 GHz) satellitesignals, through a master antenna. In the satellite broadcasting system10, a satellite receiver 100 receives the satellite signals, anddown-converts frequency bands of the satellite signals to generatecorresponding intermediate frequency (IF) signals with a frequency bandof 0.95-2.15 GHz. Then, the IF signals are transmitted to a decodingdevice 102 (e.g. a set-top box) of each user, for decoding the IFsignals. Thus, each user in the family, the building or the communitycan watch satellite broadcasting programs via various playback devices,such as a television and a computer.

In detail, a satellite receiver 100 comprises a satellite dish 110 and alow-noise block downconverter with feedhorn (LNBF) 120. Further, theLNBF 120 comprises an orthomode transducer (OMT) 122 and multiplelow-noise block downconverters (LNBs) 124. After the LNBF 120 receivessatellite signals via the satellite dish 110, the orthomode transducer122 divides the satellite signals into vertical polarization signals andhorizontal polarization signals which are outputted to the multiplelow-noise block downconverters 124. Besides, the polarization signalscan be further divided into high-band (HB) polarization signals andlow-band (LB) polarization signals according to frequency bands of thepolarization signals. That is, the polarization signals can be dividedinto LB horizontal polarization signals, HB horizontal polarizationsignals, LB vertical polarization signals and HB vertical polarizationsignals. After the low-noise block downconverter down-converts thefrequency bands of the four types of the polarization signals to theintermediate frequency of 0.95-2.15 GHz, one of the four types of thepolarization signals is outputted to the decoding device 102 of the useraccording to the choice of the user.

However, since choices of the users are usually different, a number ofthe low-noise block downconverters 124 should be proportional to anumber of types of the polarization signals and a number of the users,to provide different IF signals to the users according to the choices ofthe users. For example, each user occupies four low-noise blockdownconverters 124 of the LNBF 120, such that the each user can freelychoose one of the four types of the polarization signals. Therefore,when the number of the users is large, a large number of the low-noiseblock downconverters 124 must be installed in the LNBF 120 for servingthe users. Both cost and power consumption of the satellite receiver 100increase accordingly. Thus, how to raise the number of the polarizationsignals and the number of the users that a single low-noise blockdownconverter can serve is an important topic to be discussed.

SUMMARY OF THE INVENTION

The present invention therefore provides a MIMO low-noise blockdownconverter and a MIMO low-noise block module to solve theabove-mentioned problems.

A low-noise block downconverter (LNB) is disclosed. The low-noise blockdownconverter comprises a first input module, for outputting a firstintermediate frequency (IF) signal after receiving a first polarizationsignal via a first input end; a second input module, for outputting asecond IF signal after receiving a second polarization signal via asecond input end; a first output module, coupled to the first inputmodule, for amplifying the first IF signal, to output a first usersignal to a first user; and a second output module, coupled to thesecond input module, for amplifying the second IF signal, to output asecond user signal to a second user; wherein a first signal path and asecond signal path are coupled between the first input module and thesecond input module, the first user signal relates to the firstpolarization signal or the second polarization signal, and the seconduser signal relates to the first polarization signal or the secondpolarization signal.

A low-noise block module is disclosed. The low-noise block modulecomprises a low-noise block downconverter (LNB) and a control unit. Thelow-noise block downconverter comprises a first input module, foroutputting a first intermediate frequency (IF) signal after receiving afirst polarization signal via a first input end; a second input module,for outputting a second IF signal after receiving a second polarizationsignal via a second input end; a first output module, coupled to thefirst input module, for amplifying the first IF signal, to output afirst user signal to a first user; and a second output module, coupledto the second input module, for amplifying the second IF signal, tooutput a second user signal to a second user; wherein a first signalpath and a second signal path are coupled between the first input moduleand the second input module, the first user signal relates to the firstpolarization signal or the second polarization signal, and the seconduser signal relates to the first polarization signal or the secondpolarization signal. The control unit is used for generating a controlsignal to the low-noise block downconverter according to inputs of thefirst user and the second user, to control conducting states of thefirst signal path and the second signal path, and operations of thefirst input module, the second input module, the first output module andthe second output module, to reduce power consumption of the low-noiseblock downconverter.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a satellite broadcasting systemaccording to the prior art.

FIG. 2 is a schematic diagram of a low-noise block module according toan example of the present invention.

FIG. 3 is a schematic diagram of a low-noise block downconverteraccording to an example of the present invention.

FIG. 4 is a schematic diagram of operations of the low-noise blockdownconverter shown in FIG. 3.

FIG. 5 is a schematic diagram of a low-noise block downconverteraccording to an example of the present invention.

FIG. 6 is a schematic diagram of operations of the low-noise blockdownconverter shown in FIG. 5.

DETAILED DESCRIPTION

Please refer to FIG. 2, which is a schematic diagram of a low-noiseblock module 20 according to an example of the present invention. Thelow-noise block module 20 is used in a satellite broadcasting system,and includes a low-noise block downconverter (LNB) 22, a control unit24, an input end R1 and an input end R2. The low-noise blockdownconverter 22 is used for receiving a horizontal polarization signalS_H and a vertical polarization signal S_V via the input end R1 and theinput end R2, respectively. The horizontal polarization signal S_H andthe vertical polarization signal S_V are so-called satellite signalstransmitted on the Ku band (10.7-12.75 GHz). The control unit 24generates a control signal S_CTR, for controlling the low-noise blockdownconverter 22 to process the horizontal polarization signal S_H andthe vertical polarization signal S_V. The processing includesdown-converting frequency bands of the horizontal polarization signalS_H and the vertical polarization signal S_V to an intermediatefrequency (IF), generating corresponding IF signals and outputting usersignals S_U1 and S_U2 to two users. In short, the low-noise block module20 is a multiple-input multiple-out (MIMO) low-noise block modulecapable of receiving multiple polarization signals and generatingcorresponding user signals according to choices of the users.

Further, low-noise block downconverter 22 includes a first input module200, a second input module 202, a first output module 204, a secondoutput module 206, a signal path SL1 and a signal path SL2. The firstinput module 200 and the second input module 202 receive the horizontalpolarization signal S_H and the vertical polarization signal S_V via theinput ends R1 and R2, respectively. Then, the first input module 200 andthe second input module 202 amplify the horizontal polarization signalS_H and the vertical polarization signal S_V, down-convert frequencybands of the horizontal polarization signal S_H and the verticalpolarization signal S_V, and generate corresponding IF signals S_IF1 andS_IF2 to the first output module 204 and second output module 206,respectively. Besides, whether the frequency bands of the horizontalpolarization signal S_H and the vertical polarization signal S_V are ata high band (e.g. 11.55-12.75 GHz) HFB or a low band (e.g. 10.7-11.9GHz) LFB, the first input module 200 and the second input module 202 candown-convert the frequency bands to the same IF band (e.g. 0.95-2.15GHz) MFB by properly mixing the horizontal polarization signal S_H andthe vertical polarization signal S_V. The first output module 204 andthe second output module 206 amplify the IF signal S_IF1 and S_IF2,respectively, and generate the corresponding user signals S_U1 and S_U2to drive an output impedance. Thus, each of the two users can freelywatch satellite broadcasting programs according to his choice.

Besides, signals received or processed by the first input module 200 areoutputted to the second input module 202 via the signal path SL1;signals received or processed by the second input module 202 areoutputted to the first input module 200 via the signal path SL2. Inshort, the signals processed by the first input module 200 and thesecond input module 202 are not limited to respectively receivedpolarization signals (e.g. the horizontal polarization signal S_H andthe vertical polarization signal S_V) by using the signal paths SL1 andSL2 coupled between the first input module 200 and the second inputmodule 202.

Therefore, no matter which of low-band (LB) horizontal polarizationsignal, high-band (HB) horizontal polarization signal, LB verticalpolarization signals and HB vertical polarization signal are chosen bythe two users, the control unit 24 can generate the control signalS_CTR, for controlling conducting states of the signal paths SL1 andSL2, and controlling the first input module 200 and the second inputmodule 202 to down-convert frequency bands of the horizontalpolarization signal S_H and the vertical polarization signal S_V to theintermediate frequency. Then, the corresponding IF signals are generatedand outputted to the first output module 204 and the second outputmodule 206. In the prior art, four pairs of input/output modules arerequired in a satellite receiver for providing four types of thepolarization signals to a single user, i.e., eight pairs of theinput/output modules are required for two users. In comparison, only twopairs of the input/output modules are required in the present inventionfor providing the four types of the polarization signals to each of thetwo users. Therefore, both cost and power consumption of the satellitereceiver is reduced.

Please note that, the spirit of the present invention is to control theconducting states of the signal paths SL1 and SL2, and control the firstinput module 200 and the second input module 202 to properly mix andprocess the polarization signals, such that the two users can freelychoose either type of the polarization signals. Connections of thesignal paths SL1 and SL2, and realizations of the first input module 200and the second input module 202 are not limited, as long as theabove-mentioned features are realized. For example, please refer to FIG.3, which is a schematic diagram of a low-noise block downconverter 30according to an example of the present invention. The low-noise blockdownconverter 30 is used for realizing the low-noise block downconverter22 shown in FIG. 2, and includes a first input module 300, a secondinput module 310, a first output module 320 and a second output module330. Further, the first input module 300 includes a low-noise amplifier(LNA) 302, an oscillator 304 and a mixer 306; the second input module310 includes a low-noise amplifier 312, an oscillator 314 and a mixer316. The oscillators 304 and 314 can generate a low oscillationfrequency signal with an oscillation frequency F1 (e.g. 9.75 GHz) and ahigh oscillation frequency signal with an oscillation frequency F2 (e.g.10.6 GHz). The first output module 320 includes an IF amplifier 322 andan output buffer 324; the second output module 330 includes an IFamplifier 332 and an output buffer 334. Besides, the signal path SL1 iscoupled between the input end R1 and the low-noise amplifier 312, andthe conducting state of the signal path SL1 is controlled by the switchSW1; the signal path SL2 is coupled between the input end R2 and thelow-noise amplifier 302, and the conducting state of the signal path SL2is controlled by the switch SW2.

In detail, for example, the two users choose the HB horizontalpolarization signal and the LB horizontal polarization signal,respectively. The control unit 24 generates the control signal S_CTR,for controlling the switch SW1 closed and the switch SW2 open. In thissituation, the low-noise amplifier 302 receives the horizontalpolarization signal S_H via the input end R1, amplifies the horizontalpolarization signal S_H, and correspondingly generates an input signalS_IN1. Similarly, the low-noise amplifier 312 receives the horizontalpolarization signal S_H via the input end R1 and the signal path SL1,amplifies the horizontal polarization signal S_H, and correspondinglygenerates an input signal S_IN2. Besides, since the two users choose theHB horizontal polarization signal and the LB horizontal polarizationsignal, respectively, the control signal S_CTR also controls theoscillator 304 to generate an oscillation signal S_OC1 with theoscillation frequency F2, and controls the oscillator 314 to generate anoscillation signal S_OC2 with the oscillation frequency F1. Then, thefirst input module 300 and the second input module 310 output the IFsignals at the same IF band MFB. Therefore, after the input signalsS_IN1 and S_IN2 are processed by the mixers 306 and 316, respectively,the first input module 300 outputs the IF signal S_IF1 at the IF bandMFB to the first output module 320 and the second input module 310outputs the IF signal S_IF2 at the IF band MFB to the second outputmodule 330. In other words, the control signal S_CTR adjusts theoscillation frequencies of the oscillation signals, for outputting theIF signals at the same IF band MFB. Then, the IF amplifier 322 amplifiesthe IF signal S_IF1, and correspondingly generates an output signalS_OU1 to the output buffer 324. The output buffer 324 amplifies theoutput signal S_OU1 for driving the output impedance, andcorrespondingly generates the user signal S_U1 to the first user suchthat the first user can watch the chosen satellite broadcasting program.Similarly, the IF amplifier 332 amplifies the IF signal S_IF2, andcorrespondingly generates an output signal S_OU2 to the output buffer334. The output buffer 334 amplifies the output signal S_OU2 for drivingthe output impedance, and correspondingly generates the user signal S_U2to the second user such that the second user can watch the chosensatellite broadcasting program. For ease of illustration, please referto FIG. 4, which is a schematic diagram of a low-noise blockdownconverter 40 according to an example of the present invention. Thelow-noise block downconverter 40 is used for illustrating operations ofthe low-noise block downconverter 30 shown in FIG. 3, for example, thecorresponding responses of elements and changes of the signal pathsafter receiving the control signal S_CTR. Elements shown in FIG. 4 arerespectively the same as those shown in FIG. 3, and are not narratedherein.

As can be seen from the above, the control unit 24 generates the controlsignal S_CTR according to the choices of the two users, for controllingthe switches SW1 and SW2 to control the conducting states of the signalpaths SL1 and SL2, respectively, to provide the signal paths requiredfor transmitting the polarization signals. Besides, the control unit 24controls the oscillators to generate the oscillation frequenciescorresponding to the frequency bands of the polarization signals chosenby the two users, such that the frequency bands of the polarizationsignals are down-converted to the IF band MFB by the oscillationsignals. Then, the IF signals are outputted to the corresponding outputmodules. Please note that, the above example illustrates that the twousers choose the HB horizontal polarization signal and the LB horizontalpolarization signal, respectively. In practice, the two users can freelychoose any of the LB horizontal polarization signal, the HB horizontalpolarization signal, the LB vertical polarization signals and the HBvertical polarization signal. Therefore, the present invention providesthe four types of the polarization signals to each of the two users byusing two pairs of the input/output modules and the two signal paths.That is, 16 combinations of the polarization signals are provided to thetwo users, which greatly enhance the use efficiency of the low-noiseblock downconverters. In comparison, the four pairs of the input/outputmodules are required in the prior art for providing four types of thepolarization signals to a single user. That is, eight pairs of theinput/output modules are required in the prior art for providing fourtypes of the polarization signals to the two users. Therefore, thepresent invention reduces both the cost and the power consumption of thesatellite receiver and the low-noise block downconverter 30.

Besides, the elements such as amplifiers and buffers in the low-noiseblock downconverter 30 of FIG. 3 are simply used for illustratingallocations of corresponding types of the elements. In practice, anumber of the same type of the elements can be increased at the sameposition according to system requirement. For example, the low-noiseamplifier 302 of the first input module 300 can be replaced by multiplelow-noise amplifiers, which are the same type of the low-noise amplifier302. On the other hand, additional amplifiers can also be placed on thesignal paths SL1 and SL2 for compensating the path loss coming from longrouting traces of the signal paths SL1 and SL2. Thus, the quality of thereceived polarization signals can meet the system requirement forsuccessive signal processing. Realizations and statements mentionedabove are ordinary skills in the art. Thus, those skilled in the artshould make various alterations and modifications according to systemrequirement, and is not limited herein.

On the other hand, the present invention further adds a pair of signalpaths between the two output modules based on the low-noise block module20, such that the cost and the power consumption of the satellitereceiver and the low-noise block downconverter can be further reducedwhile the two users can freely chose the polarization signals.

Please refer to FIG. 5, which is a schematic diagram of a low-noiseblock downconverter 50 according to an example of the present invention.The low-noise block downconverter 50 is used for realizing the low-noiseblock downconverter 22 shown in FIG. 2, and includes a first inputmodule 500, a second input module 510, a first output module 520 and asecond output module 530. Further, the first input module 500 includes alow-noise amplifier 502, an oscillator 504 and a mixer 506; the secondinput module 510 includes a low-noise amplifier 512, an oscillator 514and a mixer 516. The oscillators 504 and 514 generate a low oscillationfrequency signal with an oscillation frequency F1 (e.g. 9.75 GHz) and ahigh oscillation frequency signal with an oscillation frequency F2 (e.g.10.6 GHz). The first output module 520 includes an IF amplifier 522 andan output buffer 524; the second output module 530 includes an IFamplifier 532 and an output buffer 534. On the other hand, a signal pathSL1 a is coupled between the low-noise amplifier 502 and the mixer 516,and a conducting state of the signal path SL1 a is controlled by theswitch SW1 a; a signal path SL2 a is coupled between the low-noiseamplifier 512 and the mixer 506, and a conducting state of the signalpath SL2 a is controlled by the switch SW2 a. Besides, a signal path SL3a is coupled between the IF amplifier 522 and the output buffer 534, anda conducting state of the signal path SL3 a is controlled by the switchSW3 a; a signal path SL4 a is coupled between the IF amplifier 532 andthe output buffer 524, and a conducting state of the signal path SL4 ais controlled by the switch SW4 a.

In detail, for example, the two users both choose the LB horizontalpolarization signal. The control unit 24 generates the control signalS_CTR, for controlling the switches SW1 a, SW2 a and SW4 a open andcontrolling the switch SW3 a closed. In this situation, the low-noiseamplifier 502 receives the horizontal polarization signal S_H via theinput end R1, amplifies the horizontal polarization signal S_H, andcorrespondingly generates an input signal S_IN1 a. The control signalS_CTR also controls the oscillator 504 to generate an oscillation signalS_OC1 a with the oscillation frequency F1 (e.g. 9.75 GHz). After theinput signals S_IN1 a is processed by the mixers 506, the first inputmodule 500 outputs an IF signal S_IF1 a at the IF band MFB to the firstoutput module 520. Then, the IF amplifier 522 amplifies the IF signalS_IF1 a, and correspondingly generates an output signal S_OU1 a. Theoutput signal S_OU1 a is transmitted to the output buffer 524, and isalso transmitted to the output buffer 534 via the signal path SL3 a. Theoutput buffers 524 and 534 amplify the output signal S_OU1 a for drivingan output impedance, and correspondingly generates the user signal S_U1and the user signal S_U2, respectively, to the two users. Besides, sincethe second input module 510 and the IF amplifier 532 are not used forprocessing and transmitting the polarization signals, the low-noiseblock downconverter 50 can turn off the second input module 510 and theIF amplifier 532 to reduce power consumption of the low-noise blockdownconverter 50. For ease of illustration, please refer to FIG. 6,which is a schematic diagram of a low-noise block downconverter 60according to an example of the present invention. The low-noise blockdownconverter 60 is used for illustrating operations of the low-noiseblock downconverter 50 shown in FIG. 5, for example, the correspondingresponses of elements and changes of the signal paths after receivingthe control signal S_CTR. Elements shown in FIG. 6 are respectively thesame as those shown in FIG. 5, and are not narrated herein.

As can be seen from the above, the control unit 24 generates the controlsignal S_CTR according to the choices of the two users, for controllingthe switches SW1 a and SW2 a to switch conducting states of the signalpaths SL1 a and SL2 a, respectively, and controlling the switches SW3 aand SW4 a to switch conducting states of the signal paths SL3 a and SL4a, respectively. Thus, the signal paths required for transmitting thepolarization signals are established. Besides, the control unit 24 turnsoff elements and modules which are not used for transmitting thepolarization signals to reduce the power consumption. Please note that,the above example illustrates that the two users both choose the LBhorizontal polarization signal. In practice, the two users can freelychoose any of the LB horizontal polarization signal, the HB horizontalpolarization signal, the LB vertical polarization signals and the HBvertical polarization signal. Comparing with the example of FIG. 3, theexample of FIG. 5 further improves efficiency of the low-noise blockdownconverter 50 by using the two pairs of the input/output modules andtwo pairs of the signal paths. Besides, power consumption of thelow-noise block downconverter 50 is further reduced by turning off theelements and the modules which are not used for transmitting thepolarization signals.

Besides, similar to the low-noise block downconverter 30 of FIG. 3, theelements such as amplifiers and buffers in the low-noise blockdownconverter 50 of FIG. 5 are simply used for illustrating allocationsof corresponding types of the elements. In practice, a number of thesame type of the elements can be increased at the same positionaccording to system requirement. On the other hand, additionalamplifiers can also be placed on the signal paths SL1 a, SL2 a, SL3 aand SL4 a for compensating the path loss coming from long routing tracesof the signal paths SL1 a, SL2 a, SL3 a and SL4 a to meet systemrequirement. Realizations and statements mentioned above are ordinaryskills in the art. Thus, those skilled in the art should make variousalterations and modifications according to system requirement, and isnot limited herein.

Please note that, realization of the control unit 24 is not limited, aslong as an input of a user can be identified and a corresponding controlsignal can be generated. For example, in a Ku band satellite receiver,the control unit 24 recognizes that the user chooses a horizontalpolarization signal if the input of the user includes a high voltage(e.g. 18-19 volts), and recognizes that the user chooses a verticalpolarization signal if the input of the user includes a low voltage(e.g. 13-14 volts). Besides, the control unit 24 recognizes that theuser chooses a HB polarization signal if the input of the user includesa 22 KHz tone, and recognizes that the user chooses a LB polarizationsignal if the input of the user does not include the 22 KHz tone. On theother hand, a switch of a signal path can be realized by allocating anelement (e.g. an amplifier) on the signal path. Thus, the signal path isconducting by turning on the element, and is open by turning off theelement. For example, a buffer stage can be used for realizing theswitch. When a gate bias of the buffer stage is turned on, the signalpath conducts; when the gate bias of the buffer stage is turned off, thesignal path is open.

On the other hand, when the low-noise block downconverter is used forreceiving a Ku band satellite signal, the LB LFB and HB HFB in thepresent invention refer to frequency bands of 10.7-11.9 GHz and11.55-12.75 GHz, respectively. In this situation, as long as oscillatorscan generate oscillation signals with oscillation frequencies of 9.75GHz and 10.6 GHz according to a control signal S_CTR, a LB polarizationsignal and a HB polarization signal can both be down-converted into a IFsignal at a frequency band MFB of 0.95-2.15 GHz. Therefore, the presentinvention can use MIMO to handle the Ku band satellite signal. Besides,when oscillators generating oscillation signals with oscillationfrequencies of 10.75 GHz and 11.3 GHz are used in the low-noise blockdownconverter for receiving the Ku band satellite signal, the presentinvention operates regularly after correspondingly modifying the controlsignal S_CTR and parameters of the elements. Therefore, the presentinvention can be used for broadcasting systems with various operatingfrequencies after appropriate modifications, e.g. changing oscillationfrequencies of oscillators and using low-noise amplifiers, mixers, IFamplifiers and output buffers with appropriate passbands.

To sum up, the present invention provides a MIMO low-noise blockdownconverter and a MIMO low-noise block module, wherein two pairs ofinput/out modules and one or two pairs of signal paths are installed.Thus, two users can freely choose any of a LB horizontal polarizationsignal, a HB horizontal polarization signal, a LB vertical polarizationsignals and a HB vertical polarization signal, which greatly enhancesthe use efficiency of the low-noise block downconverters. Cost and powerconsumption of the low-noise block downconverter and a satellitereceiver in which the low-noise block downconverter is installed arereduced. Besides, power consumption of the low-noise block downconverterand the satellite receiver is further reduced by turning off elementsand modules which are not used for transmitting polarization signals.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

What is claimed is:
 1. A low-noise block downconverter (LNB),comprising: a first input module, for outputting a first intermediatefrequency (IF) signal after receiving a first polarization signal via afirst input end; a second input module, for outputting a second IFsignal after receiving a second polarization signal via a second inputend; a first output module, coupled to the first input module, foramplifying the first IF signal, to output a first user signal to a firstuser; and a second output module, coupled to the second input module,for amplifying the second IF signal, to output a second user signal to asecond user; wherein a first signal path and a second signal path arecoupled between the first input module and the second input module, thefirst user signal relates to the first polarization signal or the secondpolarization signal, and the second user signal relates to the firstpolarization signal or the second polarization signal.
 2. The low-noiseblock downconverter of claim 1, wherein the first input modulecomprises: a first low-noise amplifier (LNA), for receiving andamplifying the first polarization signal, to generate a first inputsignal; and a first mixer, coupled between the first low-noise amplifierand the first output module, for mixing a first oscillation signal andthe first input signal, to down-convert a frequency band of the firstinput signal and generate the first IF signal; wherein the second inputmodule comprises: a second low-noise amplifier, for receiving andamplifying the second polarization signal, to generate a second inputsignal; and a second mixer, coupled between the second low-noiseamplifier and the second output module, for mixing a second oscillationsignal and the second input signal, to down-convert a frequency band ofthe second input signal and generate the second IF signal.
 3. Thelow-noise block downconverter of claim 2, wherein the first signal pathis coupled between the first input end and the second low-noiseamplifier, for transmitting the first polarization signal to the secondlow-noise amplifier, and the second signal path is coupled between thesecond input end and the first low-noise amplifier, for transmitting thesecond polarization signal to the first low-noise amplifier.
 4. Thelow-noise block downconverter of claim 2, wherein the first signal pathis coupled between the first low-noise amplifier and the second mixer,for transmitting the first input signal to the second mixer, and thesecond signal path is coupled between the second low-noise amplifier andthe first mixer, for transmitting the second input signal to the firstmixer.
 5. The low-noise block downconverter of claim 2, wherein thefirst input module further comprises a first oscillator, coupled to thefirst mixer, for generating the first oscillation signal, and the secondinput module further comprises a second oscillator, coupled to thesecond mixer, for generating the second oscillation signal.
 6. Thelow-noise block downconverter of claim 1, wherein the first signal pathcomprises a first switch, for switching a conducting state of the firstsignal path, and the second signal path comprises a second switch, forswitching a conducting state of the second signal path.
 7. The low-noiseblock downconverter of claim 6, wherein the first switch and the secondswitch are buffer stages, and operations of the buffer stages arecontrolled by gate bias of the buffer stages, respectively.
 8. Thelow-noise block downconverter of claim 1, wherein the first outputmodule comprises: a first IF amplifier, coupled to the first inputmodule, for amplifying the first IF signal, to output a first outputsignal; and a first output stage, coupled to the first IF amplifier, foramplifying the first output signal as the first user signal, to drive anoutput impedance and output the first user signal to the first user;wherein the second output module comprises: a second IF amplifier,coupled to the second input module, for amplifying the second IF signal,to output a second output signal; and a second output stage, coupled tothe second IF amplifier, for amplifying the second output signal as thesecond user signal, to drive an output impedance and output the seconduser signal to the second user.
 9. The low-noise block downconverter ofclaim 8, wherein the first output module further comprises: a thirdsignal path, coupled between the first IF amplifier and the secondoutput stage, for transmitting the first output signal to the secondoutput stage; and a fourth signal path, coupled between the second IFamplifier and the first output stage, for transmitting the second outputsignal to the first output stage.
 10. The low-noise block downconverterof claim 8, wherein the third signal path comprises a third switch, forswitching a conducting state of the third signal path, and the fourthsignal path comprises a fourth switch, for switching a conducting stateof the fourth signal path.
 11. The low-noise block downconverter ofclaim 10, wherein the third switch and the fourth switch are bufferstages, and operations of the buffer stages are controlled by gate biasof the buffer stages, respectively.
 12. The low-noise blockdownconverter of claim 1, wherein the first polarization signal is avertical polarization signal, and the second polarization signal is ahorizontal polarization signal.
 13. A low-noise block module,comprising: a low-noise block downconverter (LNB), comprising: a firstinput module, for outputting a first intermediate frequency (IF) signalafter receiving a first polarization signal via a first input end; asecond input module, for outputting a second IF signal after receiving asecond polarization signal via a second input end; a first outputmodule, coupled to the first input module, for amplifying the first IFsignal, to output a first user signal to a first user; and a secondoutput module, coupled to the second input module, for amplifying thesecond IF signal, to output a second user signal to a second user;wherein a first signal path and a second signal path are coupled betweenthe first input module and the second input module, the first usersignal relates to the first polarization signal or the secondpolarization signal, and the second user signal relates to the firstpolarization signal or the second polarization signal; and a controlunit, for generating a control signal to the low-noise blockdownconverter according to inputs of the first user and the second user,to control conducting states of the first signal path and the secondsignal path, and operations of the first input module, the second inputmodule, the first output module and the second output module, to reducepower consumption of the low-noise block downconverter.
 14. Thelow-noise block module of claim 13, wherein the first input modulecomprises: a first low-noise amplifier (LNA), for receiving andamplifying the first polarization signal, to generate a first inputsignal; and a first mixer, coupled between the first low-noise amplifierand the first output module, for mixing a first oscillation signal andthe first input signal, to down-convert a frequency band of the firstinput signal and generate the first IF signal; wherein the second inputmodule comprises: a second low-noise amplifier, for receiving andamplifying the second polarization signal, to generate a second inputsignal; and a second mixer, coupled between the second low-noiseamplifier and the second output module, for mixing a second oscillationsignal and the second input signal, to down-convert a frequency band ofthe second input signal and generate the second IF signal.
 15. Thelow-noise block module of claim 14, wherein the first signal path iscoupled between the first input end and the second low-noise amplifier,for transmitting the first polarization signal to the second low-noiseamplifier, and the second signal path is coupled between the secondinput end and the first low-noise amplifier, for transmitting the secondpolarization signal to the first low-noise amplifier.
 16. The low-noiseblock module of claim 14, wherein the first signal path is coupledbetween the first low-noise amplifier and the second mixer, fortransmitting the first input signal to the second mixer, and the secondsignal path is coupled between the second low-noise amplifier and thefirst mixer, for transmitting the second input signal to the firstmixer.
 17. The low-noise block module of claim 14, wherein the controlunit generates the control signal to the low-noise block downconverteraccording to the inputs of the first user and the second user, tocontrol operations of the first low-noise amplifier, the secondlow-noise amplifier, the first mixer and the second mixer, to reduce thepower consumption of the low-noise block downconverter.
 18. Thelow-noise block module of claim 14, wherein the first input modulefurther comprises a first oscillator, coupled to the first mixer, forgenerating the first oscillation signal, and the second input modulefurther comprises a second oscillator, coupled to the second mixer, forgenerating the second oscillation signal.
 19. The low-noise block moduleof claim 18, wherein the control unit generates the control signal tothe low-noise block downconverter according to the inputs of the firstuser and the second user, to control oscillation frequencies of thefirst oscillation signal and the second oscillation signal.
 20. Thelow-noise block module of claim 18, wherein the control unit generatesthe control signal to the low-noise block downconverter according to theinputs of the first user and the second user, to control operations ofthe first oscillator and the second oscillator, to reduce the powerconsumption of the low-noise block downconverter.
 21. The low-noiseblock module of claim 13, wherein the first signal path comprises afirst switch, for switching a conducting state of the first signal pathaccording to the control signal, and the second signal path comprises asecond switch, for switching a conducting state of the second signalpath according to the control signal.
 22. The low-noise block module ofclaim 21, wherein the first switch and the second switch are bufferstages, and operations of the buffer stages are controlled by gate biasof the buffer stages, respectively.
 23. The low-noise block module ofclaim 13, wherein the first output module comprises: a first IFamplifier, coupled to the first input module, for amplifying the firstIF signal, to output a first output signal; and a first output stage,coupled to the first IF amplifier, for amplifying the first outputsignal as the first user signal, to drive an output impedance and outputthe first user signal to the first user; wherein the second outputmodule comprises: a second IF amplifier, coupled to the second inputmodule, for amplifying the second IF signal, to output a second outputsignal; and a second output stage, coupled to the second IF amplifier,for amplifying the second output signal as the second user signal, todrive an output impedance and output the second user signal to thesecond user.
 24. The low-noise block module of claim 23, wherein thecontrol unit generates the control signal to the low-noise blockdownconverter according to the inputs of the first user and the seconduser, to control operations of the first IF amplifier, the second IFamplifier, the first output stage and the second output stage, to reducethe power consumption of the low-noise block downconverter.
 25. Thelow-noise block module of claim 23, wherein the first output modulefurther comprises: a third signal path, coupled between the first IFamplifier and the second output stage, for transmitting the first outputsignal to the second output stage; and a fourth signal path, coupledbetween the second IF amplifier and the first output stage, fortransmitting the second output signal to the first output stage.
 26. Thelow-noise block module of claim 25, wherein the control unit generatesthe control signal to the low-noise block downconverter according to theinputs of the first user and the second user, to control conductingstates of the third signal path and the fourth signal path.
 27. Thelow-noise block module of claim 25, wherein the third signal pathcomprises a third switch, for switching a conducting state of the thirdsignal path according to the control signal, and the fourth signal pathcomprises a fourth switch, for switching a conducting state of thefourth signal path according to the control signal.
 28. The low-noiseblock module of claim 27, wherein the third switch and the fourth switchare buffer stages, and operations of the buffer stages are controlled bygate bias of the buffer stages, respectively.
 29. The low-noise blockmodule of claim 13, wherein the first polarization signal is a verticalpolarization signal, and the second polarization signal is a horizontalpolarization signal.